This invention relates to ink eradicator systems.
Eradicator fluids which contain a reducing agent that will cause the dye component of an ink to be reduced to a colorless form are commonly used, e.g., in the graphic arts, to correct ink markings. The reducing agent used is generally a reducing sulfur compound, e.g., a sulfite salt. These fluids often suffer from the disadvantage that a new marking, made over the eradicator fluid, will also disappear due to the presence of the reducing agent.
Many solutions to this problem have been proposed. For example, in some instances a second, different ink has been used to write over the eradicator fluid. Others have proposed that the proportion of the sulfite salt in the eradicator fluid be reduced.
European Patent Application No. 0032652 teaches an eradicator fluid in which the sulfite salt reducing agent is replaced with a basic nitrogen compound. As discussed in U.S. Pat. No. 5,006,171, the resulting eradicator fluids are typically highly alkaline, which may cause damage to the paper structure such that upon overwriting the paper fibers may be pulled out.